Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60G—VEHICLE SUSPENSION ARRANGEMENTS
  • B60G17/00—Resilient suspensions having means for adjusting the spring or vibration-damper characteristics, for regulating the distance between a supporting surface and a sprung part of vehicle or for locking suspension during use to meet varying vehicular or surface conditions, e.g. due to speed or load
  • B60G17/02—Spring characteristics, e.g. mechanical springs and mechanical adjusting means
  • B60G17/04—Spring characteristics, e.g. mechanical springs and mechanical adjusting means fluid spring characteristics
  • B60G17/0416—Spring characteristics, e.g. mechanical springs and mechanical adjusting means fluid spring characteristics regulated by varying the resiliency of hydropneumatic suspensions
  • B60G17/0424—Spring characteristics, e.g. mechanical springs and mechanical adjusting means fluid spring characteristics regulated by varying the resiliency of hydropneumatic suspensions by varying the air pressure of the accumulator
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60G—VEHICLE SUSPENSION ARRANGEMENTS
  • B60G2202/00—Indexing codes relating to the type of spring, damper or actuator
  • B60G2202/10—Type of spring
  • B60G2202/15—Fluid spring
  • B60G2202/154—Fluid spring with an accumulator
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60G—VEHICLE SUSPENSION ARRANGEMENTS
  • B60G2500/00—Indexing codes relating to the regulated action or device
  • B60G2500/20—Spring action or springs

Definitions

• the invention relates to a pressure control system for adapting a hydraulic drive to changing load situations, with a hydraulic accumulator connected to the hydraulic drive, a supply device for a working medium generating the preload pressure of the hydraulic accumulator, and with a control device via which the supply device can be controlled in order to be activated of the preload pressure of the hydraulic accumulator to set the pressure characteristic of the hydraulic drive.
• the object of the invention is to create a pressure control system which is expanded in comparison and which has improved possible uses and with which a precise, continuous course of a predefinable pressure characteristic curve can be achieved.
• a corresponding object is achieved by a pressure control system having the features of claim 1.
• the supply device for the hydraulic accumulator contains a further hydraulic accumulator, which on the one hand contains the working medium generating the preload pressure of the first hydraulic accumulator and on the other hand contains a control medium whose pressure can be adjusted by means of the control device, by means of the control of the pressure of the control medium a constant and precise control of the pressure of the working medium can be achieved and thus an exact adjustment of the pressure medium Characteristic curve, for example a spring characteristic curve, which can be adapted to a wide variety of load situations.
• a further hydraulic accumulator which on the one hand contains the working medium generating the preload pressure of the first hydraulic accumulator and on the other hand contains a control medium whose pressure can be adjusted by means of the control device, by means of the control of the pressure of the control medium a constant and precise control of the pressure of the working medium can be achieved and thus an exact adjustment of the pressure medium Characteristic curve, for example a spring characteristic curve, which can be adapted to a wide variety of load situations.
• the hydraulic drive preferably consists of a linear drive, in particular in the form of a hydraulic working cylinder; however, a hydraulic motor can also be controlled as a hydraulic drive.
• the relevant drives can not only be used as spring damping systems for vehicle axles; but rather also in other areas, such as elevators and lifting platforms, but also as hydraulic drives for work machines and machine tools.
• a pressure transducer that determines the actual value of the preload pressure is connected to a computer unit (microprocessor) that evaluates the pressure values, determines the respective setpoint values for the preload pressure, and the control device for the dynamic adaptation processes are continuously controlled.
• Fig. 1 is a schematic diagram of an embodiment in use as a suspension system
• FIG. 2 shows a basic circuit diagram of a second exemplary embodiment, similar to FIG. 1, part of the control device being omitted compared to FIG. 1.
• the suspension system mentioned is used to adapt to changing loads for vehicle axles, with only a single vehicle axle 10 being shown in principle in both figures.
• a vehicle tire 1 2 is arranged rotatable about this axis 10 and, as a fixed wheel rim, can alternatively also serve to drive a chain drive (not shown).
• the use of the suspension system described here is particularly worthwhile in the construction of mobile vehicles, i.e. for heavy-duty commercial vehicles, mobile cranes, tractors, dump trucks and the like, i.e. especially for applications where high variable axle loads can occur.
• the suspension system has a hydraulic accumulator 14, which serves as a suspension accumulator and is designed in a conventional manner, for example as a membrane accumulator.
• This chamber 20, which forms the fluid side of the hydraulic accumulator 14, is connected via a connecting line 24 to a hydraulic working cylinder 26 as a linear drive on the piston side.
• At least one controllable switching valve is preferably arranged in this connecting line, in particular for switching off the fluid side of the hydraulic accumulator 14. shown embodiment, a switching valve 22 is present, which makes it possible to depressurize the fluid side of the hydraulic accumulator 14 and the working cylinder 26 if necessary.
• the working cylinder 26 serves as a suspension cylinder for the vehicle axle 10, the piston rod 28 of the hydraulic piston 34 acting directly on the vehicle axle 10.
• the spring characteristic of the working cylinder 26 can be automatically adjusted by controlling the gas preload pressure of the hydraulic accumulator 14 via a control device which has a supply device designated as a whole by 30, by means of which, as will be explained in more detail below, the pressure of a gaseous working medium can be set in accordance with the control device , which generates the gas bias pressure in the hydraulic accumulator 14.
• This supply device 30 is connected via a connecting line 32 to the chamber 18 forming the gas side of the hydraulic accumulator 14.
• the supply device 30 has a pressure transducer 36 connected to the connecting line 32, which determines the actual value of the pressure of the working medium, and thus the biasing pressure of the hydraulic accumulator 14, and emits a corresponding electrical signal to the electronics of the control device, which is not shown in detail in the drawing .
• the connecting line 32 Via a switching valve 38, which can be controlled by the control device, the connecting line 32 is connected to the gas space 40 of a further hydraulic accumulator, which is designed as a piston accumulator 42 and contains a freely movable separating piston 44, which separates the gas space 40 from the oil space 46.
• a gas valve 48 connected to the gas space serves as a filling valve for the working medium, preferably in the form of nitrogen gas.
• the oil chamber 46 of the piston accumulator 42 is connected via a line 50 to a controllable pressure supply device 52, which is part of the control device. tion is connected.
• the pressure supply device 52 enables, via a throttle 54, the controlled supply and discharge of a fluid control medium to the oil space 46 of the piston accumulator 42.
• the pressure supply device 52 has a pressure control valve 56, the connection labeled P with a pressure source for the control medium and the connection labeled T with the fluid tank is connected. With its connection designated A, the pressure control valve 56 is connected via a switching valve 58 to the throttle 54 and accordingly to the line 50 leading to the oil chamber 46.
• the switching valve 58 and the pressure control valve 56 are bridged by a pressure limiting valve 60.
• the oil supply 46 of the piston accumulator 42 is supplied with control medium by means of the pressure supply device 52 in order to move the separating piston 44 into a position corresponding to a desired biasing pressure of the working medium in the gas space 40 and to achieve an actual value determined by the pressure sensor 36 which is one of the Control device for a given load situation corresponds to predetermined target value.
• the pressure is controlled by releasing the pressure, i.e. Removal of control medium via line 50 and pressure control valve 56 until the desired preload pressure in piston accumulator 42 and in hydraulic accumulator 14 serving as suspension accumulator is reached.
• the control device is therefore programmed in such a way that the pressure control valve 56 tracks the piston 44 during the phases of the temperature compensation by supplying or removing control medium and thus keeps the pressure constant at the predetermined desired value.
• a proportionally adjustable pressure control valve 56 is preferably provided for automation by building a pressure control circuit.
• the embodiment shown in Fig. 2 differs in principle from the first described example in that the connecting line 24 between the hydraulic accumulator 14 serving as a spring accumulator and the working cylinder 26 is connected via an additional valve control 62 interacting with the control device (not shown) and in particular in that for the determination of the actual value of the preload pressure, ie of the pressure of the working medium, no pressure sensor 36 is provided. Rather, in the example of FIG. 2, a device for detecting the piston travel of the separating piston 44 is provided in the piston accumulator 42. This piston travel detection device, designated 64 in FIG. 2, generates a control signal representing the position of the separating piston 44 within the piston accumulator 42 for delivery to the control device.
• a certain actual gas pressure value can be assigned to each piston position.
• a certain piston position is approached. This is effected via the line 50 in a manner corresponding to that in the first described embodiment by means of the pressure supply device 52, which is not shown in FIG. 2, which accordingly supplies the control medium to the oil chamber 46 of the piston accumulator 42 or removes it from the latter.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Vehicle Body Suspensions (AREA)
• Fluid-Pressure Circuits (AREA)
• Control Of Transmission Device (AREA)

Applications Claiming Priority (3)

Publications (2)

Family

ID=7873336

Family Applications (1)

Country Status (4)

Cited By (1)

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Family Cites Families (7)

• 1998
  • 1998-07-08 DE DE19830506A patent/DE19830506A1/de not_active Ceased
• 1999
  • 1999-03-22 EP EP99919136A patent/EP1094959B1/fr not_active Expired - Lifetime
  • 1999-03-22 AT AT99919136T patent/ATE265329T1/de not_active IP Right Cessation
  • 1999-03-22 DE DE59909345T patent/DE59909345D1/de not_active Expired - Fee Related
  • 1999-03-22 WO PCT/EP1999/001916 patent/WO2000002743A1/fr active IP Right Grant

Non-Patent Citations (1)

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